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Monday, April 25, 2011

Each year, on or about the 25th of April, the Adelie penguins of Ross Island leave their brooding grounds and swim to their winter sanctuary northwest of the Balleny Islands. Some decided to mark the occasion by including all penguins and dubbing the day World Penguin Day.

Most penguins do participate in migratory habits. Why they favor some places more than others as their destination is the current work of biologists. Current belief is that the Adelies favor a place that has more pack ice, thereby providing more protection. This appears to be true, as the Davis Station Adelies migrate north, then west, staying close to the Antarctic continent. Also, Antarctica's days become much shorter and the Adelies do not feed well in the dark. Traveling north, these birds have longer days in order to fish and feed.

Other penguins migrate, as well. The Magellanic penguins of South America travel to Mar del Plata, where usually there is more food and less harsh conditions; however, in the past few years, the Magels have suffered many losses due to inadequate food. The Falkland Island Rockhopper Penguins have traditionally migrated to coastal South America, and the northernmost of the colonies favored the areas along the Patagonian Shelf. The Macaronis stay in the sub-Antarctic area, mostly at sea, during their migration from their breeding grounds.

These are just a few instances of penguin migration; the point is that they do migrate and when they do, this action initiates the end of the breeding season and the beginning of a new life in the vast southern ocean for thousands of newly molted juveniles.

Tuesday, April 19, 2011

Nothing is black-and-white, it seems. Not even penguins. That’s what University of Texas paleontologist Julia Clarke found after unearthing 36-million- year-old remains in Peru’s Paracas National Reserve—the first penguin fossil ever found with evidence of feathers intact. Like its present-day relatives, Inkayacu paracasensis was a deft swimmer. Unlike them, it weighed more than a hundred pounds and sported a coat with ruddy feathers. Clarke’s team deduced the color last year after comparing tiny pigment packages called melanosomes from the fossilized plumage with those of living species. This part of coastal Peru has recently produced other big penguin finds. Clarke says the area could be key to painting the full picture of the birds’ evolution. For now, a touch of color has been applied. —Catherine Zuckerman

Thursday, April 14, 2011

Evolution in birds of the olfactory bulb, the part of the brain where smell information is processed, passing from a dinosaur (Bambiraptor) through early birds (Lithornis, Presbyornis) to a modern-day bird (pigeon). (Credit: Courtesy of WitmerLab at Ohio University)

ScienceDaily (Apr. 13, 2011) — Birds are known more for their senses of vision and hearing than smell, but new research suggests that millions of years ago, the winged critters also boasted a better sense for scents.

A study published April 12 by scientists at the University of Calgary, the Royal Tyrrell Museum and the Ohio University College of Osteopathic Medicine tested the long-standing view that during the evolution from dinosaurs to birds, the sense of smell declined as birds developed heightened senses of vision, hearing and balance for flight. The team compared the olfactory bulbs in the brains of 157 species of dinosaurs and ancient and modern-day birds.

The findings, published in the journal Proceedings of the Royal Society B, dispute that theory. The scientists discovered that the sense of smell actually increased in early bird evolution, peaking millions of years ago during a time when the ancestors of modern-day birds competed with dinosaurs and more ancient branches of the bird family.

"It was previously believed that birds were so busy developing vision, balance and coordination for flight that their sense of smell was scaled way back," said Darla Zelenitsky, assistant professor of paleontology at the University of Calgary and lead author of the research. "Surprisingly, our research shows that the sense of smell actually improved during dinosaur-bird evolution, like vision and balance."

In an effort to conduct the most detailed study to date on the evolution of sense of smell, the research team made CT scans of dinosaurs and extinct bird skulls to reconstruct their brains. The scientists used the scans to determine the size of the creatures' olfactory bulbs, a part of the brain involved in the sense of smell. Among modern-day birds and mammals, larger bulbs correspond to a heightened sense of smell.

"Of course the actual brain tissue is long gone from the fossil skulls," said study co-author Lawrence Witmer, Chang Professor of Paleontology at the Ohio University College of Osteopathic Medicine, "but we can use CT scanning to visualize the cavity that the brain once occupied and then generate 3D computer renderings of the olfactory bulbs and other brain parts."

The study revealed details of how birds inherited their sense of smell from dinosaurs.

"The oldest known bird, Archaeopteryx, inherited its sense of smell from small meat-eating dinosaurs about 150 million years ago," said François Therrien, curator of dinosaur palaeoecology at the Royal Tyrrell Museum and co-author of the study. "Later, around 95 million years ago, the ancestor of all modern birds evolved even better olfactory capabilities."

How well did dinosaurs smell, especially compared to modern animals? Although scientists haven't been able to make an exhaustive comparison, Witmer noted that the ancient beasts most likely exhibited a range of olfactory abilities. T. rex had large olfactory bulbs, which probably aided the creature in tracking prey, finding carcasses and possibly even territorial behavior, while a sense of smell was probably less important to dinosaurs such as Triceratops, he said.

The team was able to make some direct comparisons between the ancient and modern-day animals under study. Archaeopteryx, for example, had a sense of smell similar to pigeons, which rely on odors for a number of behaviors.

"Turkey vultures and albatrosses are birds well known for their keen sense of smell, which they use to search for food or navigate over large areas," says Zelenitsky. "Our discovery that small Velociraptor-like dinosaurs, like Bambiraptor, had a sense of smell as developed as turkey vultures and albatrosses suggests that smell may have played an important role while these dinosaurs hunted for food."

If early birds had such powerful sniffers, why do birds have a reputation for a poor sense of smell? Witmer explained that the new study confirms that the most common birds that humans encounter today -- the backyard perching birds such as crows and finches, as well as pet parrots -- indeed have smaller olfactory bulbs and weaker senses of smell. It may be no coincidence that the latter are also the cleverest birds, suggesting that their enhanced smarts may have decreased the need for a strong sniffer, he said.

Other authors on the article include Amanda McGee, a graduate student at the University of Calgary, and Ryan Ridgely, a research associate in the WitmerLab at Ohio University. The research was funded by grants to Zelenitsky from the Natural Sciences and Engineering Research Council of Canada and to Witmer and Ridgely from the U.S. National Science Foundation.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Ohio University, via EurekAlert!, a service of AAAS.

ScienceDaily (Apr. 11, 2011) — Fluctuations in penguin populations in the Antarctic are linked more strongly to the availability of their primary food source than to changes in their habitats, according to a new study published online on April 11 in the Proceedings of the National Academy of Sciences. Funded in part by the Lenfest Ocean Program, this research indicates that species often considered likely "winners" of changing conditions, such as large-scale ice melting, may actually end up as the most vulnerable to the impacts of climate change.

The two penguin species of focus in the study rely on small shrimp-like creatures known as krill for their survival. A previous assessment in Nature of krill in the Southern Ocean suggests that their abundance has declined as much as 80 percent since the 1970s.

"For penguins and other species, krill is the linchpin in the food web. Regardless of their environmental preferences, we see a connection between climate change and penguin populations through the loss of habitat for their main food source," said Dr. Wayne Trivelpiece, lead author and seabird researcher of the National Oceanic and Atmospheric Administration's Antarctic Ecosystem Research Division. "As warming continues, the loss of krill will have a profound effect throughout the Antarctic ecosystem."

A 30-year field study of Adélie (ice-loving) and chinstrap (ice-avoiding) penguins shows that populations of both species in the West Antarctic Peninsula and Scotia Sea have declined by respective averages of 2.9 and 4.3 percent per year for at least the last 10 years. Some colonies have decreased by more than 50 percent. Lack of an abundant supply of krill has been particularly hard on fledgling penguins that must learn where to locate and how to catch the prey on their own, having never been at sea before. Data from the study suggest that fewer young penguins are surviving this transition to independence today than in previous years when these crustaceans were much more abundant.

Although chinstrap penguins avoid feeding in icy habitats, sea ice provides the necessary environment for krill to reproduce. Increasing temperatures and reductions in sea ice have made conditions unfavorable to sustain ample populations of this food source. The authors suggest that fishing for krill and increased competition among other predators also have made them less available to penguins.

"Penguins are excellent indicators of changes to the biological and environmental health of the broader ecosystem because they are easily accessible while breeding on land, yet they depend entirely on food resources from the sea. In addition, unlike many other krill-eating top predators in the Antarctic, such as whales and fur seals, they were not hunted by humans," said Dr. Trivelpiece. "When we see steep declines in populations, as we have been documenting with both chinstrap and Adélie penguins, we know there's a much larger ecological problem."

Adélie penguins, which feed in icy habitats, are also declining due to food shortages and shrinking habitat. They differ from chinstrap penguins, however, in that they have breeding populations outside of the western Antarctic, which makes them less vulnerable to the rapid warming in the Antarctic Peninsula region by comparison.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Pew Environment Group, via EurekAlert!, a service of AAAS.

Pew Environment Group (2011, April 11). Penguins that shun ice still lose big from a warming climate. ScienceDaily. Retrieved April 12, 2011, from http://www.sciencedaily.com­/releases/2011/04/110411152535.htm

Sunday, April 10, 2011

ScienceDaily (Apr. 9, 2011) — Researchers from the Wildlife Conservation Society, the University of Washington, and other groups are grappling with a wildlife mystery: Why are some penguin chicks losing their feathers?

The appearance of "naked" penguins -- afflicted with what is known as feather-loss disorder -- in penguin colonies on both sides of the South Atlantic in recent years has scientists puzzled as to what could be causing the condition.

A study on the disorder appears in a recent edition of the journal Waterbirds. The authors of the paper are: Olivia J. Kane, Jeffrey R. Smith, and P. Dee Boersma of the Wildlife Conservation Society and the University of Washington; Nola J. Parsons and Vanessa Strauss of the South African Foundation for the Conservation of Coastal Birds; and Pablo Garcia-Borboroglu and Cecilia Villanueva of Centro Nacional Patagónico.
"Feather-loss disorders are uncommon in most bird species, and we need to conduct further study to determine the cause of the disorder and if this is in fact spreading to other penguin species," said Boersma, who has conducted studies on Magellanic penguins for more than three decades.

The feather-loss disorder first emerged in Cape Town, South Africa in 2006, when researchers for the South African Foundation for the Conservation of Coastal Birds (SANCCOB) first observed the disorder in African (or black-footed) penguins in a rehabilitation center. During that year, approximately 59 percent of the penguin chicks at the facility lost their feathers, followed by 97 percent of the chicks at the facility in 2007, and 20 percent of the chicks in 2008. Chicks with feather-loss disorder, it was discovered, took longer to grow to a size deemed suitable for release into the wild. The chicks eventually began growing new feathers.
One the other side of the South Atlantic, researchers from WCS and the University of Washington observed feather-loss disorder in the chicks of wild Magellanic penguins (closely related to African penguins) for the first time in 2007 in four different study sites along Argentina's coastline. Researchers also noted that while feathered chicks sought out shade in the hot midday sun, featherless chicks remained in the sun's glare. Several of the chicks with feather-loss disorder died during the study.

In both instances, penguin chicks with feather-loss disorder grew more slowly than feathered chicks. Featherless chicks were also smaller in size and weight than feathered chicks; both disparities were due to the increased energy spent in thermoregulation in the absence of an insulating coat of feathers and/or down. So far, the possible causes include pathogens, thyroid disorders, nutrient imbalances, or genetics.

"The recent emergence of feather-loss disorder in wild bird populations suggests that the disorder is something new," said Mariana Varese, Acting Director of WCS's Latin America and Caribbean Program. "More study of this malady can help identify the root cause, which in turn will help illuminate possible solutions."
"We need to learn how to stop the spread of feather-loss disorder, as penguins already have problems with oil pollution and climate variation," said Boersma. "It's important to keep disease from being added to the list of threats they face."